Dynamo-electric machine



June 14,1927.

' H. K. SCHRAGE DYNAMO ELECTRIC MACHINE Filed June 11. 1925 I 2 Sheets-sheet l Inventor: Htdde K.Schr-age.

LsAttorneg June 14, 1927. 1,632,628

H. K. SCHRAGE DYNAMO ELECTRIC MACHINE Filed June 11, 1925 2 Sheets-Sheet 2 Inventor:

} IHdde K5chrage,

Hi5 Attorney.

ill)

l etented June 14, 1927.

HIDDE K. SCHRAGE, OF PARIS, FRA

CORPORATION OF NEW YORK.

DYNAMO-ELECTRZC MACHINE.

Application filed June 11, 1925.

My invention relates to a commutator generator or shunt-excited motor capable of being operated in connection with either direct or alternating current systems and arin simple i1 anner. vention relates to a compound mo electric machine of the type having load and 1 ranged to have its characteristics controlled In particular my inwound dynaabove mentioned shunt excitation brushes which are independently adjustable with respect to the commutator whereby the no load characteristics of the be adjusted by means oi the ciated with the shunt characteristics may be adjusts the machine may brushes asso-- field and the load d by varying position of the load brushes.

It is known that under special conditions an alternating current machine will come up to saturation from netisin and will operate its remnant magin a stable manner at a definite frequency and voltage. 1 propose to provide such a commutator machine capable of having its characteristics determined by the position of its this manner of adpistinent the iarv devices brushes. By use of auxilis not essential and the control of the machineis greatly simplified.

lvly invention on reference to when considered companying drawing and its pointed Referring now shows a machine in which my been embodied; Figs. 2, 3 the magnetic tied by shitting the brushes;

will be better understood the following description in connection with the acscope will be out in the appended claims. to the drawing,

Fig. 1 invention has and t show how field of the machine is modi- Fig. 5 shows how the brushes of the machine may be shifted to vary the terminal voltage without altering the phase of the magnetic field; Fig. 6 shows the machine provided with a compensating winding; and Fig.

7 shows a compound machine with independently adustable load and excitation brushes.

Fig. 1

shows a machine provided with a rotatable commutatorwinding 1. The wind- 1 is interconnected 2 through one pair of posed brushes 3 and with with the field winddiametri-cally opfield winding a through another pair of diametrically opposed brushes 5, the field windings 2 and l being in quadrature with brushes 3 and 5 being shown equi-distant points around the located on the machine stator each other member and the as-located at periphery of Serial No. 36,523, and in France July 1, 1924.

11 B, A SIG-NOR TO GENERAL ELECTRIC COMPANY,

the coinii'iutator. As illustrated the machine is adapted tor use in connection with a twophase system. the field windings and brushes in The precise arrangement of each case will of course be determined by the number of phases.

As hereinafter explained the machine may be operated either as a generator or motor in connection with a directcurrent, single phase or Fig. 2 shows obtain in one phase of polyphase system.

the flux conditions which the machine when the pairs of brushes and are shifted from the position shown in Fig, 1 through the angle a in the direction of the machines rotation as pair of brushes indicated by the arrow 6.

5 and the field winding l The have been omitted in order to simplify the ngure. Assuming the machine to mg at certain speed traverse the circuit comprising be rotatand a current i to the field winding 2 and the armature winding 1, the

flux produced by the be represented by (,0 the in}: the winding 1 by 0 machine flux due to by p. By brushes 3 stator flux (p field winding 9 produced by and the resultant or the windings 1 and 2 change in the position of the the phase relation between the and the rotor llllX (p may be ma y altered and with each change in this relation the position 01' the resultant flux 2 in space is varied.

W'ith the brush position shown by Fig. 2 the resultant flux (p is perpendicular to the axis of the in line with the brushes '5.

brushes 3 and directly Under these conditions rotation of the winding 1 in the between the brushes 3 a voltage which tends to maintain the current 2' and to render the machine selt exciting.

The circuit comprising the field winding l will be unaffected by rotation of the winding 1 in the flux (p since the axis of this flux is parallel to the .aXis of brushes 5 which interconnect the windings i and l.

The indicated positionot the flux (p is therefore stable and the machine will operate as a direct current generator or motor.

From the position shown by Fig. 2 the brush pairs 3 and 5 may be simultaneously shifted in either a clockwise or clockwise direction.

Fig. 3 indicates obtain when the counterthe flux relations which brushes are shifted in a clockwise direction, the rotation of the machine being clockwise as indicated by the arrow 6. For this brush position,

as in that til) of Fig. 2, the flux produced by the current 1', in the winding 2 is represented by the vector (p and that produced by this current in the rotor winding 1 is represented by the vector In this case it will be observed that the resultant flux (,0 is not perpendicular to the axis of the brushes 3 but has a component in line with these brushes and a component (p perpendicular to the axis of I these brushes and in line with the axis of brushes 5. The flux component like the flux of Fig. 2, produces a voltage between the brushes 3 whieh'tends to maintain the current i At the same time the flux component (p produces between the brushes a voltage giving rise to a current i in the circuit comprising the windings 4 and 1 and this current produces a flux displaced from the flux (p by 90 degrees in the direction of machine rotation. This flux produces a voltage between the brushes 3 which tends to diminish the current 27,. The resultant flux therefore is not stable in the position shown in Fig. 3 but will move in the direction of the machines rotation. Now the flux produced by current 2' has a com ponent along the axis of the brushes 3 which tends to maintain the current 71 The resultant flux will therefore be rotated in a clockwise direction until the component flux e4 decreases to zero and the current i, disappears. At this time the flux of the machine may be represented by the vector displaced 90 degrees from the vector (p in the direction of the machines rotation. The flux (p has a component along the axis of the brushes 5 which will produce a current 2' in the windings 1 and 2 thereby tending to reduce the current in the same manner as the current i, was reduced by the current The machine flux will therefore move into a. position where it is opposed to its original position as indicated by the vector (p- .lfn a manner which will be clear from what has'been said previously the machine flux will further rotate into a position opposed to the vector as and later into the position indicated by the vector (p and will continue to rotate thereafter until the operating conditions of the machine are changed.

For a given speed of the rotor the speed at which the flux rotates will depend on the magnitude of the angle a through which the brushes are moved and upon the impedance of the exciting circuits. If the impedance of the excitation circuits is constant, the rotational speed of the flux and therefore the frequency of the machine current will decrease as the angle a is made larger. When tain when the brushes 3 and 5 are moved in a clockwise direction from the position shown by Fig. 2. As before, the flux produced by the current i, in the winding 2 is represented by the vector (p the rotor flux by the vector 1 and the machine flux by the Vector (p. As in the case of Fig. 3 the flux (p has a component (p in the axis of brushes 3 which produces a voltage causing a current i to flow in the circuit comprising windings 1 and 4, the winding 4 being omitted to avoid complexity in the figure. By the current i there is produced a flux (p displaced 90 degrees from (p in a counterclockwise direction. This flux (p has a component in the axis of the brushes 5 which tends to decrease the current i, and a component in the axis of the brushes 3 which tends to maintain the current i The machine flux is therefore not stable but will rotate in a counter-clockwise direction and at a rate of speed dependent on the magnitude of the angle through which the brushes have been shifted from the position indicated in Fig. 2. The frequency of the machine current is therefore determined by the amount of brush shift from the position of Fig. 2 and its phase sequence is determined by the direction in which the brushes are shifted.

Fig. 5 illustrates how the machine voltage may be regulated independently of the frequency. If the brushes 3 are shifted in opposite directions through equal angles, the flux (p is still perpendicular to the axis of the brushes 3 and the machine will operate as a direct current machine with the volt-age reduced somewhat below that which would obtain with the brush arrangement indicated by Fig. 2. It thus appears that the voltage of the machine depends to a large extent on the separation of the brushes in the same. phase while the frequency of its current depends to a large extent on the position of the axis of the brushes. It is thus possible to regulate more or less independently the voltage and frequency of the machine simply by displacement of the brushes and without the use of auxiliary devices. To this end the corresponding brushes of each brush pair may be mounted on one brush ring and the other brushes of each brush pair may be mounted on a different brush ring, the two brushrings being moved simultaneously in the same direction to vary the frequency and simultaneously in opposite directions to vary the voltage.

Up to this point the machine has been considered as operating at no load, i, 17 being its exciting currents. It will be apparent however that it may be operated either as a motor or a self excited generator. WVhen operated as a generator the load current may be taken from the brushes 3 and 5, from the brushes 3 or 5 alone, or from one brush 3 the angle or is increased to a value at which the flux (,0 is in the axis of the brushes 5 the machine flux is stationary and the machine will be a direct current machine as pointed out in connection with Fig. 2.

Fig. 4 shows the flux relations which oband one brush 5. As hereinafter pointed out certain important results may be obtained if separate brushes are provided to carry the load current, the brushes 3 and 5 being utilized solely to carry the exciting current of the machine. The load brushes may be fixed or movable and need not carry currents of the same number of phase as the exciting brushes. The load may be connected in series with the field windings of the machine as is done in a series direct current machine. In this case the machine is self exciting and operates with series characteristics and regulable frequency. By the pro vision of both series and shunt iield windings the machine may be made to have the characteristics of a compound machine. The machine may thusbe arranged to have the characteristics of shunt, series or compound machine and can be made to supply direct current, single phase current or polyphase current at voltage and frequency regulated simply by the displacement of its brushes.

It will be observed that, in the absence of a compensating winding or ether suitable means for neutralizing the effect of the load current on the flux (p, the magnitude and position of this flux will be affected by the load current. Fig. 6 shows how the volt ac and frequency of the machine may be e .dered independent of its load. In this figure, 7 indicates one phase of a compensating winding which is connected in series with the rotor winding 1 and the load terminals 8 through load brushes 9. The other windings are the same as those described in connection with the preceding figures. With this arrangement the exciting current is carried by the brushes 3 and 5 andthe load current by the pair of brushes 9 and corresponding pairs of brushes in the other phases it the machine supplies polyphase current. The load current is indicated by the arrow head i The winding '4 may be so designed that the current 2', does not affect the field of the machine or may be made to modify the effect of the load current on the voltage and frequency of the machine. The frequency of the machine current may therefore be stabilized at a value dependent upon the position of the brushes.

Voltage stability is dependent upon the degree of magnetic saturation. It is well known that the voltage of a direct current machine with shunt excitation is stable only when operated at quite a strong saturation or in other words at a fairly high voltage. For the same reason the machine under consideration does not operate well at low voltages. l/Vith brush control of the voltage applied to the external circuit, however, it is a comparatively simple matter to maintain the saturation of the machine at a high value since by the use of separate load and exerting brushes the load terminal voltage of the machine may be readily changed without modifying the voltage of the exciting circuits. The saturation and voltage stability of the machine are therefore quite independ cut of its terminal voltage.

In Fig. 7 a compound machine is reprcsented having an impedance 10 in the shunt excitation circuit and having itsload brushes adjustable. Referring to Fig. '7 it will apparent that at no load this n'uichine with the series iield acts, so far as the shunt exitation is concerned, as the machine of Fig. 1. Thus we can regulate the relation between the speed and the self-excitation frequency by displacing the brushes 3, 3. By providing an adjustable impedance 10 in the shunt excitation circuits we can further modify the saturation of the machine and the relation of excitation frequency to speed. Thus, for a certain speed the shunt excitation of the machine may be determined by the impedance 10 and the position of the brushes 3, 3 in such a way as to give exactly the frequency and voltage of the load terminals of the machine. At this d the 't; chine may operate as a motor at no load deriving its no load losses from the line or the machine may run as no load motor supplying wattless current to the line for power factor correction. Since the same result may be obtained for different speeds it is evident that the speed and current of the machine may be varied at no load by ad justment of the shunt excitation circuits in the manner hereinbefore explained. .Vhcn load is put on the motor it will be evident that the magnetic flux varies on account ot the ampere turns due to load current unless the machine is exactly compensated as de scribed in connection with Fig. 6. In t .e'.

7 where the load brushes afle displaced in the direction of rotation from the axis of the series winding 7 and load is applied to the motor, the speed naturally decreases with load. The difference between the no load speed and full load speed varies in proportion to such displacement of the load brushes without appreciably changing the no load speed. Thus this machine may operate from the line as a motor. The no load speed and power factor may be set by adjusting the brushes 3, 3 and the impedance 10 and the influence of the load current as regards speed and power factor under load may be regulated by displacement of the load brushes 9, 9. It is also evident that the load brushes 9, 9 may be more or less separated in the same manner as the shunt excitation brushes as explained in connection with 5.

In the case of Fig. 6 where the load brushes are assumed to be fixed, it is apparent that any of the useful means may be employed to improve commutation. In this case the load brushes may be made the line 8 at Pill ill?

but

somewhat wider and of a lower resistance than the shunt excitation brushes as represented in Fig. 6.

I have explained my invention by illustrating and describing certain specific embodiments thereof, but it will be readily understood by those skilled in the art that the invention may be embodied in many other forms than those shown and described. I, accordingly, do not wish to be restricted to the particular forms of construction disclosed herein by way of example for the purpose of setting forth my invention in accordance with the patent statutes. The terms of the appended claims are, therefore, not restricted to the precise structure disclosed, but are intended to cover all changes and modifications within the spirit and scope of my invention.v

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. A dynamo electric machine comprising a poly-phase shunt field winding, a com pounding winding, an armature winding movably related to said field windings, a commutator for said armature winding, shunt excitation brushes associated with said commutator for transmitting current from said armature winding to said poly-phase shunt field winding, load brushes independent of said shunt excitation brushes associated with said commutator, and circuits for connecting said load brushes in series with said compounding field, said shunt ex citation and load brushes being independently adjustable.

2. A dynamo electric machine comprising a poly-phase shunt field winding having independent phases, a compounding winding, an armature winding rotatably related to said field windings, a pair of shunt excitation brushes associated with said commutator for each phase of said shunt field winding, the brushes of each pair being relatively adjustable, load brushes associated on said commutator independently adjustsaid shunt excitation brushes and circuits for connecting the armature winding and compound winding in series with said load brushes.

3. A dynamo electric machine comprising a poly-phase shunt field'winding, a. compounding winding, an armature winding ro tatably related with respect to said field windings, a commutator for said armature winding, shunt excitation brushes associated with said commutator for transmitting current from said armature winding to said poly-phase shunt field winding, load brushes independent of said shunt excitation brushes associated with said commutator, circuits for connecting said load brushes in series with said compounding field, said load and shunt brushes being independently adjustable, and means for varying the shunt excitation independently of the adjustment of said shunt excitation brushes.

4. A dynamo electric machine comprising a stator member provided with a poly-phase shunt field winding having the phases independent, and a compounding winding, a rotatable armature winding provided with a commutator associated with said stator member, a pair of shunt excitation brushes for each phase of said shunt field winding, said brushes being relatively adjustable with respect to each other and to said stator member, load brushes on said commutator independently adjustabie with respect to said shunt field brushes, means for connecting said armature and compounding winding in series with said load brushes, and means for "arying the shunt field excitation of said machine independently of the adjustment of said shunt field brushes.

In witness whereof, I have hereunto set my hand this 29th day of May, 1925.

HIDDE K. SCHRAGE. 

